media-sound/drobilla: new use flags gtk3, socket and webkit; correct slot dependency on webkit-gtk
media-sound/drobilla: enable the socket use flag by default
media-sound/ingen: add the socket USE flag.
media-sound/drobilla: capitalize Ingen in metadata.xml
drobilla.eclass: Don't use unnecessary in_iuse logic when doc is always in the USE flags.
media-sound/ingen: remove unnecessary doc dependencies.
media-sound/drobilla: remove unnecessary doc dependencies.